A saliva ejector is an apparatus which includes a suction line and a saliva ejector tip. The saliva ejector tip is inserted into the patient's mouth and suction is applied via the suction line to evacuate saliva and other debris from the patient's mouth. Per convention, the saliva ejector tip is a single use device that is replaced between each patient, while the suction line may be replaced or cleaned after it has been used with several patients. Unfortunately, fluids from the previous dental patient or patients may remain in the suction line when the saliva ejector is used on subsequent patients.
A common practice is to have patients close their lips around the low-volume saliva ejector tip and "spit" to help evacuate the mouth. Closing the lips around the ejector tip can cause a decrease in the vacuum line pressure. This may allow the previously evacuated fluid remaining in the suction line to flow backwards, or back flow, into the patient's mouth. This fluid can carry oral contaminants such as blood, viruses, bacteria, and fungi. It has been found that oral bacteria can survive inside of the suction line, and that diseases including influenza, strep, and hepatitis B could be passed to subsequent patients if the suction line back flows into the patient's mouth.
In order to decrease the possibility of the back flow of fluids into a dental patient's mouth, dentists and hygienists may instruct their patients not to close their lips around the saliva ejector tips so as to prevent a decrease in the vacuum line pressure. However, a problem exists with this approach in that the saliva ejector tip may still get wedged in a position in the patient's mouth, for instance in the cheek folds, to cause a decrease in the vacuum line pressure resulting in back flow.
Another approach for decreasing the chance of oral contaminants being passed from patient to patient is to clean or change the suction line after every patient. However, this approach is time consuming and cost prohibitive. Furthermore, if the suction line is rinsed with a germ killing rinse, any remaining rinse residue in the suction line may back flow into a subsequent patient. This circumstance would be unpleasant for the dental patient or possibly dangerous depending on the caustic nature of the rinse.
In one prior art saliva ejector, the saliva ejector tip includes at least one unregulated vacuum release aperture. This aperture is simply a hole made in a tubular sidewall of the ejector tip and is spaced from the mouthpiece of the saliva ejector tip such that when the mouthpiece is inserted into a patient's mouth, the patient's mouth will not block the aperture. If the patient's lips close around the mouthpiece, a vacuum will not develop because air from the room will be drawn through the aperture. A problem with this device is that the fluid matter may leak out of the aperture when the patient's mouth is being evacuated which causes oral contaminants to be released into the room.
Another prior art device is a saliva ejector tip with an integral valve. The valve system is made up of an internal plunger in the end of the ejector tip and is inserted into the patient's mouth. This plunger is pushed into a valve seat to close off the tip thereby eliminating the sucking noise produce by the saliva ejector. The dental personnel or the patient can then close off the tip with a hand when the ejector tip is removed from the mouth or the patient can close the valve using his or her teeth. Unfortunately, this device exacerbates the back flow problem because this configuration intentionally causes a decrease in the vacuum line pressure which results in back flow.
Yet another prior art device is a valve which includes a chamber and a tubular member positioned in the chamber. The tubular member has one or more reversely lipped fins for providing a tortuous path to limit back flow of oral contaminants. However, a problem with this device is that it does not prevent the back flow or oral contaminants, it merely limits the flow. Furthermore, due to the complex construction of this valve, it is difficult to clean and costly for single use applications.